Spoonable creams are well known in Great Britain. Although the rheological parameters of creams and emulsions are defined in P. Sherman, Emulsion Science, Academic Press 1968, the term spoonable is not defined therein. According to our definition, a spoonable cream should display the following theological behaviour at 5.degree. C.
1) the yield value (also called: yield stress) should be more than 50 Pa extrapolated from shear rates between 100-300 S.sup.-1 (Bingham); PA1 2) the Bingham viscosity should be less than 500 mPa s between shear rates of 100-300 S.sup.-1 ; PA1 3) the failure to stress should occur at a strain of less than 0.5 Radians, preferably less than 0.1 Radians.
Yield values and Bingham viscosities were determined utilising the Carrimed Rheometer. Measurements were performed at 5.degree. C., using 4.degree. cone and plate geometry. The shear stress was increased from zero at a rate of 60 Pa/min, and shear rates were measured until values in excess of 600 s.sup.-1 were achieved. The experiment was then terminated. A graph of shear stress vs shear rate was plotted, and a straight line fitted to the curve between the shear rates of 100-300 s.sup.-1. The slope of this line was the Bingham viscosity. The yield stress was determined by extrapolation of this line back to zero shear rate.
The failure to stress measurements were determined utilising the Carrimed Rheometer. Measurements were performed at 5.degree. C., using a 4.degree. cone and plate geometry. The experiments performed were torque sweeps in oscillation mode. The samples were oscillated at a frequency of 1 Hz, as the torque was increased from 50-5000.mu.Nm in thirty steps. The measurement time at each torque value was 10 sec, and the time between measurements was 5 sec. The parameters measured were storage modulus (G.sup.I), loss modulus (G.sup.II) and strain (in radians). A graph of G.sup.I and G.sup.II vs strain was then plotted. At low strain values the samples displayed solid-like characteristics, and G.sup.I &gt;G.sup.II. At higher strain values G.sup.II &gt;G.sup.I and the failure to stress was defined as the strain at which G.sup.I =G.sup.II.
Low fat soured creams, based on dairy fats are known from J. of Dairy Science 86, Ann. Meeting Am. Dairy Sciency Ass 74 (1991), Aug. 12-15, Suppl. 1. These creams contain stabilisers, such as gelatin, modified starch, guar gum, locust bean gum, carrageenan, or pectins. As the rheological parameters are not mentioned, it remains unanswered whether these products meet our criteria for spoonability.
It is further known from DE 1,692,584 that unctuous food products, based on milk protein and vegetable fat (fat contents: 1-50 wt %) can be obtained when the compositions contain edible organic acids and an emulsifier combination and optionally a small amount of gelatin. According to this document it is essential that a combination of different locust bean gums is present. It can not be concluded from this document, whether the rheology of the product makes it spoonable or not.
It is for the purpose of obtaining healthier products, i.e. products containing more unsaturated or at least fewer saturated fatty acid moieties, that attempts have been made to produce a low-fat equivalent of a soured, spoonable dairy cream. However, so far any efforts to produce a soured, spoonable low-fat cream, thus one containing at least a vegetable fat in levels up to 15 wt. % with the desired properties have been unsuccessful:
Either the stability or the rheology of the creams was insufficient.
Therefore, so far no low-fat equivalent of a soured, spoonable non-dairy cream with the required properties was available.